Rubber composition and method of preserving rubber



Patented May 7, 1935 PATENT OFFICE RUBBER COMPOSITION AND METHOD OF PRESERVING RUBBER Waldo L. Semon, Cuyahoga Falls, and Arthur W.

Sloan, Akron, Ohi

o, assignors to The B. F.

Goodrich Company, New York, N. Y., a corporation of New York No Drawing. Application August 22, 1928,

Serial No. 301.440

58Claims.

The invention relates to the art of preserving rubber, either in the vulcanized or unvulcanized condition, and to rubber compositions so preserved.

It is well known that rubber gradually loses its strength and resiliency, particularly when exposed to light, heat, and air, such deterioration being commonly attributed to an oxidation of the rubber or the rubber composition. Various substances, known generally as age-resisters or anti-oxidants, have been added to rubber for the purpose of retarding its deterioration. Among the most successful of these substances are the secondary aromatic amines and the condensation products of aldehydes with primary aromatic amines.

This invention, in brief, consists in treating rubber with a member of a new class of age-resisters, namely, condensation products of ketones with primary aromatic amines. Such substances in general have age-resisting properties, but the best results were secured by using the condensation products of amines with aliphatic ketones. It was also found that substituted or condensed ring amines produced more active products than the simpler amines. Thus p-toluidine produces considerably better condensation products than aniline, and alpha-naphthylamine still better. However, any primary aromatic amine, such as aniline, the toluidines, the xylidines, anisidine, phenetedine, p-phenylene-diamine, alpha and beta naphthylamine, the naphthylene diamines, mono or diamino-diphenylamine, etc., may be condensed with ketones such as acetophenone, benzophenone, benzoyl acetone, cinnamone, hydroxy benzal acetone, dibenzal acetone, benzoin, etc., but preferably with aliphatic ketones such as acetone, cyclohexanone, acetyl acetone, mesityl oxide, phorone, diacetone alcohol, hydroxy acetone, hydracetyl acetone, etc. The unsaturated or hydroxy-substituted aliphatic ketones appear to give particularly good condensation products with primary aromatic amines. Any one of the above-mentioned class of ketone-amine condensation products may be incorporated into rubber or a rubber composition with beneficial efiects on its age-resisting properties, preferably from 0.2 to 5 parts by weight to 100 parts of rubber being used.

Many of these condensation products are oils or viscous liquids which are particularly easy to incorporate into rubber, and which soften unvulcanized rubber stocks and permit them to be worked readily on the calender or tubing machine.

Example 1.As a specific example of one embodiment of the method of this invention, the condensation product of cyclohexanone and alpha-naphthylamine was prepared by mixing 30 parts by weight of cyclohexanone and 45 parts of alpha-naphthylamine. The mixture was heated under a reflux condenser for 8 hours, during which time the materials reacted and split out water. The excess of unreacted materials was finally removed by distilling up to a temperature of 340 F. A typical tire tread composition was prepared containing blended plantation rubbers 100 parts by weight, sulfur 5.5 parts, zinc oxide 30 parts, gas black 40 parts, mineral rubber 10 parts, palm oil 5 parts, and hexamethylene tetramine 0.75 part. One part of this was used as a control. To another part was added 0.95 part by weight (0.5% of the composition) of the condensation product prepared as described above. The compositions were thoroughly mixed, and vulcanized in a press for 45 minutes at 294 F. to produce an optimum cure. The vulcanized compositions were tested to compare their relative rates of aging, by measuring their tensile strength and elongation at the'breaking point before and after aging. The accelerated aging was carried out in the Geer aging oven, in which the samples were maintained .at a temperature of 158 F. in a constantly renewed current of air. The results are shown in the table below.

Tensile strength in lbs. per sq. in. and elongation at the breaking point 35 After 7 days in the Before ag n Geer oven Tensile strength Tensile Elongastrength Elongation,

tlon

Per cent 667 685 Per cent Without age-resister With age-resistor After 7 days in the Before ag Gear oven Tensile strength Tensile Elongastrength tion Elongation Per cent Per cent 690 687 Without age-resister.-

th age-resistor Example 3.-As another specific example of the process of this invention, condensation products were prepared of diacetone alcohol with aniline and with alpha naphthylamine in approximately equimolecular proportions. In the one case parts by weight of diacetone alcohol were mixed with 93 parts of aniline, and in the other case with 143 parts of alpha naphthylamine, and the mixtures were heated to drive oil the water formed by the reaction. The products were respectively dark red and black syrupy liquids. The products were incorporated into rubber compositions and the vulcanized compositions tested before and after aging as in Example 1 above, with the following results:

Tensile strength in lbs. per sq. in. and elongation at the breaking point After 7 days in the Botom aging Gear oven Tensile strength Tensile Elo strength 1188 Elongation tion Per cent 3628 623 Per cent Without ageresister 450 With diacetone alcoholaniline With diacetone alcoholalpha naphthylamine- From the examples given above it is evident that the condensation products of ketones and aromatic amines are extremely efiective in retarding the deterioration which rubber normally undergoes upon aging. Obviously the proportions of the materials used in the rubber composition may be varied to meet any individual requirements, or rubber compositions of a widely different nature, such as inner tube, tire friction, hose cover, pure gum thread or other compositions may be employed, the beneficial effect of the addition of a ketone-amine condensation product being observed in general in rubber exposed to oxidation. These condensation products may also be applied to unvulcanized or vulcanized rubber with good effect on the age-resisting properties of the rubber, such as by ap-' plying them to the surface of the rubber, as for example in solution, or in the form of a paste or emulsion.

It is to be understood that the term treating as employed in the appended claims is used in a generic sense to include either the incorporation of the condensation products of ketones and aromatic amines into the rubber by milling or similar process, or by mixing with the rubber latex before coagulation, or to the application thereof to the surface of a mass of crude or vulcanized rubber. The term rubber is likewise employed inthe claims in a generic sense to include caoutchouc, balata, gutta percha, rubber isomers and like products, whether or not admixed with fillers, pigments, vulcanizing or accelerating agents. The word "aryl is herein employed to refer to univalent aromatic hydrocarbon radicals whose free valence belongs to the nucleus and not to a side chain.

While we have herein disclosed with considerable particularity certain preferred manners of performing our invention, we do not thereby desire or intend to limit ourselves solely thereto, for, as hitherto stated, the precise proportions of the materials utilized may be varied and other materials having equivalent chemical properties may be employed if desired without departing from the spirit and scope of the invention as defined in the appended claims.

We claim:

1. The method of preserving rubber which comprises treating rubber with the condensation product of an unsaturated aliphatic ketone with a primary aromatic amine.

2. The method of preserving rubber which comprises treating rubber with the condensation product of an unsaturated aliphatic ketone with a primary arylamine.

3. The method of preserving rubber which comprises treating rubber with the condensation product of an unsaturated aliphatic ketone with alpha-naphthylamine.

4. The method of preserving rubber which comprises treating rubber with the condensation product of mesityl oxide with alpha-naphthylamine.

5. The method of preserving rubber which comprises treating rubber with the condensation product of an aliphatic hydroxy ketone with a primary aromatic amine.

6. The method of preserving rubber which comprises treating rubber with the condensation product of an aliphatic hydroxy ketone with a primary arylamine.

7. The method of preserving rubber which comprises treating rubber with the condensation product of an aliphatic hydroxy ketone with alpha-naphthylamine.

8. The method of preserving rubber which comprises treating rubber with the condensation product of diacetone alcohol with alphanaphthylamine.

9. A composition of matter comprising rubber and the condensation product of an unsaturated aliphatic ketone with a primary aromatic amine.

- 10. A composition of matter comprising rubber and the condensation product of an unsaturated aliphatic ketone with alpha-naphthylamine.

11. A composition of matter comprising rubber and the condensation product of mesityl oxide and alpha-naphthylamine.

12. A composition of matter comprising rubber and the condensation product of an aliphatic hydroxy ketone with a primary aromatic amine.

13. A composition of matter comprising rubber and the condensation product of an aliphatic hydroxy ketone with alpha-naphthylamine.

14. A composition of matter comprising rubber and the condensation product of diacetone oxygen atoms with an aromatic amine consistingsolely of the elements carbon, hydr flen and nitrogen and containing only one primary amino group.

16. The method of preserving rubber which comprises treating rubber with the reaction product of an aliphatic ketone containing not more than two oxygen atoms with an aromatic amine consisting solely oi. the elements carbon. hydrogen and nitrogen and containing only one primary amino group.

17. The method of'preserving rubber which comprises treating rubber with the reaction product of a dialwl ketone with an aromatic amine consisting solehr of the elements carbon, hydrogen and nitrogen" and containing only one primary amino group.

18. The method of preserving rubber which comprises treating rubber with the reaction product of acetone and an aromatic amine consisting solely of the elements carbon, hydrogen and nitrogen and containing only one primary amino group. i

19. The method of preserving rubber which comprises treating rubber with the reaction product of a ketone containing not more than two oxygen atoms with a primary aromatic monoamine consisting solely of the elements, carbon, hydrogen and nitrogen.

20. The method of preserving rubber which comprises treating rubber with the reaction product of a ketone containing not more than two oxygen atoms with a primary aryl mono-amine.

21. The method of preserving rubber which comprises treating rubber with the reaction product of an aliphatic ketone containing not more than two oxygen atoms with a primary aryl mono-amine.

22. The method of preserving rubber which comprises treating rubber with the reaction product of an aliphatic ketone containing not more than two atoms of oxygen with a primary aromatic mono-amine consisting solely of the elements carbon, hydrogen, and nitrogen.

23. The method of preserving rubber. which comprises treating rubber with the reaction product of a dialkyl ketone with a primary aryl mono-amine.

24. The method of preserving rubber which comprises treating rubber with the reaction product of a dialkyl ketone with a primary aromatic mono-amine consisting solely of the elements carbon, hydrogen and nitrogen.

25. The method of preserving rubber which comprises treating rubber with the reaction product of acetone with a primary aromatic monoamine consisting solely of the elements 'carbon, hydrogen and nitrogen. v

26. The method of preserving rubber which comprises treating rubber with the reaction product of acetone with a primary aryl monoamine.

27. The method of preserving rubber which comprises treating rubber with the reaction product of diacetone alcohol with a primary aromatic mono-amine consisting solely of the elements carbon, hydrogen and nitrogen.

28. The method of preserving rubber which comprises treating rubber with the reaction product of diacetone alcohol with a primary arylamine.

29. A composition of matter comprising rubber and. the reaction product of a. ketone containing not more than two oxygen atoms with an aromatic amine consisting solely of the elements carbon, hydrogen and nitrogen and containing only one primary amino group.

30. A composition of matter comprising rubber and the reaction product of an aliphatic ketone containing not more than two oxygen atoms with an aromatic amine consisting solely of the elements carbo hydrogen and nitrogen and containing only one primary amino group.

31. A composition of matter comprising rubber and the reaction product of a dialkyl ketone with an aromatic amine consisting solely of the elements carbon, hydrogen and nitrogen and containing only one primary amino group.

32. A composition of matter comprising rubber and the reaction'product of acetone and an aromatic amine consisting solely of the elements carbon, hydrogen and nitrogen and containing only one primary amino group.

33. A composition of matter comprising rubber and the reaction product of a ketone containing not more than two oxygen atoms with a primary aromatic mono-amine consisting solely of the elements carbon, hydrogen and nitrogen.

34. A composition of matter comprising rubber and the reaction product of a ketone containingnot more than two oxygen atoms with a primary aryl mono-amine.

35. A composition of matter comprising rubber and the reaction product of an aliphatic ketone containing not more than two oxygen atoms with a primary aryl mono-amine.

36. A composition of matter comprising rubber and the reaction product of an aliphatic ketone containing not more than two atoms of oxygen with a primary aromatic mono-amine consisting solely of the elements carbon, hydrogen, and nitrogen.

37. A composition of matter comprising rubber and the reaction product of a dialkyl ketone with a primary aryl mono-amine.

38. A composition of-matter comprising rubber and the reaction product of a dialkyl ketone with a primary aromatic mono-amine consisting solely of the elements carbon, hydrogen and nitrogen.

39. A composition of matter comprising rubber and the reaction product of acetone with a primary aromatic mono-amine consisting solely of the elements carbon, hydrogen and nitrogen.

40. A composition of matter comprising rubber and the reaction product of acetone with a primary aryl mono-amine.

41 A composition of matter comprising rubber and the reaction product of diacetone alcohol with a primary aromatic mono-amine consisting solely oi the elements carbon, hydrogen and nitrogen. a

42. A composition of matter comprising rubber and the reaction product of diacetone alcohol with a primary arylamine.

43. A vulcanized rubber composition which has been vulcanizedin the presence of a reaction product of a ketone containing not more than two oxygen atoms with an aromatic amine consisting solely of the elements carbon, hydrogen and nitrogen and containing only one primary amino group.

44. A vulcanized rubber composition which has been vulcanized in the presence of a reaction product of an aliphatic ketone containing not more than two atoms of oxygen with a primary aromatic mono-amine consisting solely of the elements carbon, hydrogen and nitrogen.

45. A vulcanized rubber composition which has been vulcanized in the presence of a reaction product of a diallgvl ketone with a primary aromatic mono-amine consisting solely of the elements carbon, hydrogen and nitrogen.

46. A vulcanized rubber composition which has been vulcanized in the presence of the reaction product of a dialkyl ketone with a primary aryl mono-amine.

47. A vulcanized rubber composition which has been vulcanized in the presence of a reaction product of acetone with a primary aromatic mono-amine consisting solely of the elements carbon, hydrogen .and nitrogen.

48. A vulcanized rubber composition which has been vulcanized in the presence of the reaction product of acetone with a primary aryl mono-amine.

49. The process of manufacturing a vulcanized rubber product possessing age resisting characteristics which comprises incorporating with said product, prior tovulcanization, a reaction product of a ketone containing a methyl group attached to the carbon atom of the ketone group and a naphthylamine.

50. The process of manufacturing a vulcanized rubber product possessing age resisting characteristics which comprises incorporating with said product prior to vulcanization, a reaction product of acetone and alpha naphthylamine.

51. The .process of manufacturing a vulcanized rubber product possessing age resisting characteristics which comprises incorporating with said product, prior to vulcanization, a reaction product of substantially equi-molar portions of acetone and alpha naphthylamine.

52. An age resisting rubber product comprising the vulcanization product of a rubber stock containing, prior to the vulcanization of said stock, a reaction product of a ketone containing a methyl group attached to the carbon atom of the ketone group and naphthylamine.

53. An age resisting rubber product comprislng the vulcanization product of a rubber stock containing, Prior'to the vulcanization of said stock, a reaction product of acetone and alpha naphthylamine.

;54. An age resisting rubber product comprising the vulcanization product of a rubber stock containing, prior to the vulcanization of said stock, the reaction product of substantially equimolar portions of acetone and alpha naphthylamine.

55. The process of manufacturing a vulcanization rubber product possessing age resisting characteristics which comprises incorporating with said product prior to vulcanization a reaction product of a ketone containing a methyl group attached to the carbon atom of the ketone group and alpha naphthylamin'e.

56. An age resisting rubber product comprising the vulcanization product of a rubber stock containing, prior to the vulcanization of said stock, the reaction product of a ketone containing a methyl group attached to the carbon atom of the ketone group and alpha naphthylamine.

57. The process of manufacturing a vulcanized rubber product possessing age resisting characteristics which comprises incorporating with said product, prior to vulcanization, a reaction product of a naphthylamine and a member of a group of compounds consisting of acetone and acetophenone.

58. An age resisting rubber product-oomprising the vulcanization product of a rubber stock containing, prior to the vulcanization of said stock, a reaction product of a naphthylamine and a member of a group of compounds consisting of acetone and acetophenone.

warm 1.. euros. ARTHUR w. BIDAN. 

